style(theme): 客户端切换深色视觉风格

lib/pages/auth/auth_form_widgets.dart

@@ -268,7 +268,7 @@ class _ModeSegment extends StatelessWidget {
         duration: _segmentDuration,
         alignment: Alignment.center,
         decoration: BoxDecoration(
-          color: selected ? AppColors.blue : Colors.transparent,
+          color: selected ? AppColors.blue : AppColors.transparent,
           borderRadius: BorderRadius.circular(18),
         ),
         child: Stack(

lib/pages/auth/auth_view.dart

@@ -258,7 +258,7 @@ class _AuthPageState extends State<AuthPage> {
   Widget build(BuildContext context) {
     final l10n = AppLocalizations.of(context)!;
     return Theme(
-      data: AppTheme.light(),
+      data: AppTheme.dark(),
       child: Scaffold(
         resizeToAvoidBottomInset: false,
         backgroundColor: AppColors.ink,

lib/pages/auth/auth_widgets.dart

@@ -141,7 +141,7 @@ class _AuthModeSwitch extends StatelessWidget {
       style: TextButton.styleFrom(
         minimumSize: const Size(0, _minTapTarget),
         padding: EdgeInsets.zero,
-        overlayColor: Colors.transparent,
+        overlayColor: AppColors.transparent,
         splashFactory: NoSplash.splashFactory,
         shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(22)),
       ),

lib/pages/auth/phone_auth_sheet.dart

@@ -28,8 +28,8 @@ Future<bool?> showPhoneAuthSheet(BuildContext context, {bool signUp = false}) {
     context: context,
     isScrollControlled: true,
     useSafeArea: true,
-    backgroundColor: Colors.transparent,
-    barrierColor: Colors.black.withValues(alpha: 0.62),
+    backgroundColor: AppColors.transparent,
+    barrierColor: AppColors.mediaBlack.withValues(alpha: 0.62),
     builder: (_) => PhoneAuthSheet(initialSignUp: signUp),
   );
 }